Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 46: Organic Thin Films III

DS 46.1: Talk

Friday, March 26, 2010, 14:00–14:15, H8

Role of the substrate in electronic structure, molecular orientation, and morphology of organic thin films: diindenoperylene on rutile TiO2(110) — •Maria Benedetta Casu, Britt-Elfriede Schuster, Indro Biswas, and Thomas Chassé — IPTC, University of Tübingen, Tübingen, Germany

Diindenoperylene (DIP, C₃₂H₁₆) is a perylene-based molecule that shows a very high hole mobility already in thin films, good film forming properties, and thermal stability. Sample preparation and photoemission experiments (X-ray photoelectron spectroscopy, XPS) were carried out in an ultrahigh vacuum system, The Ti 2p core level photoemission spectrum showed only a very weak low binding energy shoulder usually attributed to surface non-stoichiometry due to oxygen vacancies (3-5 % in our clean substrates). Atomic force microscopy (AFM) measurements were performed under ambient conditions in tapping mode. Near edge X-ray absorption spectroscopy (NEXAFS) measurements were performed at the beamline UE52-PGM at BESSY (Berlin). The results of our multitechnique investigation performed on diindenoperylene thin films deposited on rutile TiO₂(110) show island growth, with crystallites nucleating preferentially along the [1-10] substrate crystallographic axis. The findings evidence that the film properties at the interface are common to what found for a number of organic molecules deposited on the same substrate, revealing that the structural and morphological properties of organic thin films on rutile TiO₂(110) are essentially driven by its surface topography, with its rows of bridging oxygen atoms, while the molecular properties are less relevant.